TOI-6651 b
Astrophysical Synthesis & Habitability Characterization
TOI-6651 b is a confirmed sub-neptune exoplanet orbiting the star TOI-6651, located approximately 691.9 light-years (212.13 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0735% across the stellar disk), this world measures 5.09 Earth radii (0.45 Jupiter radii) and has a measured mass of 61 Earth masses (0.19 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.55 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 2.35 g⊕ (23.05 m/s²), and an escape velocity of 38.7 km/s.
In its orbital architecture around TOI-6651, TOI-6651 b completes one full revolution every 5.057 Earth days at a semi-major axis of 0.0633 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 136.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.091 carries the world between 0.0575 AU at periapsis and 0.0691 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1493 K (+1220°C / +2228°F) and receiving 817.00 S⊕ (~1,111,937 W/m²), TOI-6651 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-6651 is classified as a stellar host with an effective photospheric temperature of 5,940 K, a radius of 1.721 R☉, a mass of 1.323 M☉, an estimated bolometric luminosity of 3.308 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.71 Gyr and a metallicity of [Fe/H] = 0.225 dex (metal-rich relative to the Sun). From Earth, TOI-6651 shines at apparent V-band magnitude 10.242 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-6651 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,940 K |
| Stellar Radius | 1.7210 R☉ |
| Stellar Mass | 1.3230 M☉ |
| Bolometric Luminosity | 3.308 L☉ |
| Metallicity [Fe/H] | 0.225 dex |
| Stellar Age | 3.710 Gyr |
| Apparent Magnitude | V: 10.242 · G: 10.042 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.063300 AU |
| Orbital Period | 5.057 days |
| Mean Orbital Velocity | 136.2 km/s |
| Orbital Eccentricity (e) | 0.09100 |
| Orbital Inclination (i) | 84.9300° |
| Mean Bulk Density | 2.55 g/cm³ (38.7 km/s vesc) |
| Insolation Flux | 817.0000 S⊕ (~1,111,937 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 691.900 LY (212.128 pc) |